Reaction product of dextran-modified polyester with organic diisocyanate and method of producing same



'dextran of lower molecular weight.

United States Patent-O my REACTION PRODUCT OF DEXTRAN-MODIFIED POLYESTER WITH ORGANIC DIISOCYANATE AND METHOD OF PRODUCING SAME Leo J. Novak, Dayton, Ohio, assignor to The Common-' wealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio No Drawing. Application March 15, 1955 Serial No. 494,566

-3 Claims. (Cl; 260-9) between thermoplastic and thermosetting and may be hardened by cooling or by heating but at temperatures lower than are usually required for the setting ofpolyesters, v

This and other objects of the invention are achieved by the provision of new products which are polyesters including dextran as a co-reactant and further modified by reaction with organic diisocyanates.

The polyesters are obtained by heating dextran, at least one unsaturated polycarboxylic acid, anhydride or functional derivative of the acid, and at least one poly- 2,933,463 Patented Apr. 19,1960

may, be varied and either the polycarboxylic acid or polyhydric alcohol may predominate, the dextran being used, usually, in relatively smalleriamount. For instance, the-dextran modified, resinous partial condensation product may be obtained by heating a mixture of, by weight, 30% to 75% of the polycarboxylic acid, anhydride or substituted acid, from 15% to 60% of the polyhydric alcohol, and from 5% to 25% of the dextran, the total of these ingredients equalling 100%. The three materials maybe mixed together directly or the dextran, or a portion thereof, may be dissolved or dispersed in the poly,- hydric alcohol with heating, and the solution or dispersion added to the liquid acid or anhydride, the mass being heated with agitation to reaction temperature and until a homogeneous, fluid dextran-modified partial condensate is obtained, at, which time the heating is discontinued. Temperatures of 50 C.,to'300 C. may be used.

The organic diisocyanate is mixed with the dextranmodified partial condensation product or reactive polyester before the latter is setin the completely reacted or condensed condition and, during such setting, reacts with thepolyester to extend the chainsthereof and, depending on the amount of the diisocyanate used, may also cross.-

link the polyester chains.

The organic isocyanates as a class may be used. Typical are 4,4'-diphenyl diisocyanate, -4,4'-diphenylene meth: ane diisocyanate,'dianisidine diisocyanate, 4,4-tolidene diisocyanate, 1,5 naphthalene diisocyanate, 4,4'-diphenyl ether diisocyanate, and pphenylene diisocyanate. The diisocyanateis used in an amount of 0.50 to 1.5 mole per rnol ofthedextran-rriodifiedpolyester. Mixtures of diisocyanates may be used to impart the rubber-like properties to the'dextran-modified polyesters.

As noted, the polyesters modified by co-reaction of the acid and; alcohol withdextran differ from the straight polyester or those mixed with copolymerizable cr'osslinking monoethylenically unsaturated monomers of the styrene type in being on the borderline between thermohydric alcohol together until a dextran-modified fluid partial condensation product of the acid and alcoholis obtained;

Unsaturated polycarboxylic acids which maybe used include.maleicffumaric, phthalic and citraconic acids, their anhydrides, and such substituted unsaturated polycarboxylic acids or functional derivatives as chlormaleic, chlorfumaric, methylethyl maleic, diethyl maleic and chloromethyl maleic acids. Typical polyhydric alcohols are ethylene glycol, di-, trior tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, glycerol or pentaerythritol.

The dextran may be synthesized from sucrose by the 1 action of microorganisms of the Leuconostoc mesmteroides and L. dextranicum types. The procedure is to inoculate an appropriate sucrose-bearing nutrient medium with a culture of the microorganism or the'enzymefilt'ered from the culture, incubate the mass until the dextran is produced in maximum yield, separate the dextran from the fermentate, purify it and, for the presentpurposes, reduce it to particulate condition. This native product having very high molecular weight calculated to be in the millions may be usedor it may be hydrolyzed to In general the dextran component of resin may have amolecular weight between 5000 and that of the native material. Microorganisms which may be used to synthesize the dextran include those bearing the following NRRL (Northern Regional Research Laboratory) designations: Leuconostoc mesenteroides B-5l2, B-119, B-1146, B-1l90, B-742, B-119l, B-l208, B-12l6, B-ll20, B-l144, B-523; Streptobacterium dextranicum B+1254and Be tabacterium vermiforme B-ll39.

The relative proportions of the respective components plastic and thermosetting, thedextran serving as a co-- reacted control which to the extentof the amount thereof present functions to diminish the thermosetting property.

The dextran-modified' polyesters may be set by either heating or cooling, but more expeditiously under one'or the other condition depending on the alcohol constituent of the polyester. Those partial condensates derived from glycerol or other alcohol of more than two hydroxyl groups tend tobe more definitely thermosetting and may be more expeditiously set by heating, the temperatures required being lower, however, than are needed, ordinarily, to set a polyester resin in ajpractical time period. Temperatures of 50 C to C. may be used for times varying inversely with the temperature between two hours and 30 minutes. The polyesters from glycerol or. the like may be set, also, at room temperature, somewhat longer setting times being needed.

Those dextran-modified,polyesters derived from dihydric alcohols ;like.ethylene' glycol, on the other hand, tend to be more definitely thermoplastic and may be most expeditiously set by. cooling, These polyesters 1 modified partially'condensed polyester takes place during settingof the polyester but usually proceeds more rapidly under mild heating.

Ordinarily, in modifying polyesters with organic diisocy'anates, the reactive number (sum of the acid and hydroxyl numbers)- is critical. The presence of the dextran asco-reactantin the polyester. also has the effect oimaking then obtaining of a tough but workable prod net on reactiorr of the organic diisocyanate with the. polyester less dependent on the reactive number since the dextran presents a high proportion of free hydroxyl groups which tend to insure plasticity or flexibility in the product even when the'acid number going to make ,up the reactive number is higher than is permissible in the absence of the dextran.v Also, in the case of the dextran-modified polyesters organic diiso'cyanates as a "class may be used to impart the elastomeric properties. The following examples are. illustrative of specific embodiments of the invention, it being understood that these examples are not intended as limitative.

. Example I A dextran-modified polyester is prepared by dissolving 14.3 parts of particulate L. m. 'B-S 12 dextran (aver- 'age M.W. 30,000) in 40.4 parts of hot glycerol, adding the hot solution to 45.3 parts of melted maleic anhydride, and boiling the mass for -15 minutes with con- Example II Example I is repeated using a polyester obtained by dissolving 10.2 parts of particulate native L. m. B-512 dextran in 16.2 parts'of hot glycerol, mixing that hot tinuous stirring. About 5 parts of 4,4'-diphenyl diisosolution with 51.3 parts of melted maleic anhydride containing 10.3 parts of the dextran, and boiling the mass for 12 minutes with constant stirring until a clear,

homogeneous dextran-modified partially condensed polyester is obtained. 7

Example III Other dextrans of molecular weight in the range given herein, other acids and alcohols of the type stated, and other organic diisocyanates when used in the manner exemplified, yieldthe elastomeric resins.

About 8 parts In processing the products on the rubber mill, curing thereof may be facilitated by the incorporation of additional diisocyanate (the same as or different from that already present in the product). Or other conventional curing agents may be added on the mill, such as alkyl ethers or hexamethylol melamine with a 2,4-dihalo naphthol as accelerator, as well as such polyisocyanates as 4,4,4-triisocyanto triphenyl methane, 1,3,5-triisocyanto benzene and 2,4,6-triisocyanto toluene. The amount of curing agent added may vary somewhat and may be from 1% to 3% by weight of the modified polyester.

' The elastomeric dextran-modified polyesters of the invention may be used as replacement, substitute, or extender for natural or known synthetic rubbers and applied for the purposes for which those materials are adapted, as for instance in tires, belts, hose, sheet packing, gaskets, molded goods, floor mats, dipped goods, sheeting, tank lining, covered rolls and other mechanical and industrial goods. products may be prepared with the aid of dispersing and stabilizing agents and applied asflexible coating to various bases such as paper, textiles, metal foil, etc., the coatings only needingto be dried atroom or moderately elevated temperatures. carboxymethyl dextran is an efiective dispersing and stabilizing agent for the elastomeric products. in aqueous media, but other materials which facilitate dispersion of the products aque- 4 ous media may also be used, including such dispersing and wetting agents as fatty acid soaps particularly amine soaps of the type of triethanolamine oleate or ricinoleate, sulfated alcohols, sulfonated ethers, sulfonated amide derivatives and the like.

The dispersions may be made in kneading or mixing machines or on roller mills.

Example IV An aqueous dispersion of the product of Example I is prepared by sheeting out 50 parts of the product on a rubber mill, slowly adding to it, on the rolls, a paste of 3 parts carboxymethyl dextran derived from L. m. B-512 native dextran and containing an average of 2.9 carboxymethyl groups per anhydroglucopyranosidic unit, 5 parts triethanolamine oleate, and 5 parts concentrated ammonium hydroxide in 90 parts of water. About 40 parts of water are added on the rolls and after milling for 45 minutes, the product is put in a mixer and diluted with 190 parts of water containing 2.5 parts of concentrated ammonium hydroxide. The resulting dispersion is useful, pigmented or clear, as protective or decorative finish for paper, textiles, leather, metal foil, etc.

As will be apparent, various changes and modifications may be made within the scope of the disclosure in practicing the invention. It is to be understood, therefore, that it is not intended to limit the invention except as defined in the appended claims.

What is claimed is:

1..A resinous composition prepared by heating and reacting a mixture in parts by weight of (1) a dextranmodified resin produced by heating a mixture consisting of 30% to 75% of a substance selected from the group consisting of unsaturated polycarboxylic acids and their acid anhydrides, 15% to of a monomeric polyhydric alcohol and5% to 25% of dextran to a temperature of about 300 C., and (2) to the resultant mass introducing and reacting therewith 0.5 to 1.5 mols of an .organic diisocyanate per mol of said dextran-modified resin. r

2. The method of making a resinous composition which comprises mixing and. reacting an organic diisocyanate with a dextran-modified resin obtained by heating a mixture of 30% to-75% of a substance selected from the group consisting of unsaturated polycarboxylic acids and their acid anhydrides, 15% to 60% of a monomeric polyhydric alcohol and 5% to 25% of dextran, in an amount of 0.5m 1.5 mols of the diisocyanate per mol of said dextran-modified resin, and holding the mixture at the reaction temperature until it is set in hard, tough, elastomeric condition.

3. A resinous composition prepared by dissolving in parts by weight of 14.3 parts of particulate Leuconostac mesenteroides' NRRL B-5l2 dextran (average M.W. 30,000 in 40.4 parts of hot glycerol, adding the hot solution to 45.3 'parts of melted maleic anhydride, boiling the mass for 10-15 minutes with continuous stir- Aqueous dispersions of these ring, and thereafter introducing 5 parts of 4,4'-diphenyl diisocyanate to the resultant melt, and then pouring the mass into a tray coated with carnauba wax and heated for 5 hours at C.

References Cited in the file of this patent UNITED STATES PATENTS 2,282,827 Rothrack May 12, 1942 2,624,768 Toulmin Jan. 6, 1953 2,625,535 Mastin Jan. 13, 1953 2,809,176 Wenzelberger Oct. 8, 1957 2,823,188 Novak Feb. 11, 1958 OTHER REFERENCES Flory: Journal of Physical Chemical Chemistry, volume 1942) pages 132 to 140. p 

1. A RESINOUS COMPOSITION PREPARED BY HEATING AND REACTING A MIXTURE IN PARTS BY WEIGHT OF (1) A DEXTRANMODIFIED RESIN PRODUCED BY HEATING A MIXTURE CONSISTING OF 30% TO 75% OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF UNSATURATED POLYCARBOXYLIC ACIDS AND THEIR ACIDS ANHYDRIDES, 15% TO 60% OF A MONOMERIC POLYHYDRIC ALCOHOL AND 5% TO 25% OF DEXTRAN TO A TEMPERATURE OF ABOUT 300*C., AND (2) TO THE RESULTANT MASS INTRODUCING AND REACTING THEREWITH 0.5 TO 1.5 MOLS OF AN ORGANIC DIISDOCYANATE PER MOL OF SAID DEXTRAN-MODIFIED RESIN. 